Schema and migrations

Calling store.ensure() creates:

• anvia_memory_sessions
• anvia_memory_messages
• anvia_memory_errors
• a unique ordered-message index

Messages and errors reference their session with cascading deletes. Appends run in a BEGIN IMMEDIATE transaction and positions are unique within a memory session.

The session table includes nullable compaction_state_json. It stores the latest summary checkpoint and canonical message boundary; compaction does not remove covered messages. store.ensure() adds the column when upgrading an adapter-managed database. For application-managed schemas, add the nullable text column in a reviewed migration before calling store.validate().

Use createSqliteMemorySchemaSql() when provisioning the same schema through application migrations, then call store.validate() at startup. Upgrades still require diffing the generated DDL, reviewing the source changelog, and testing against a copy of production data.

Back up the database with an SQLite-aware workflow. Copying a live file without accounting for journaling can produce an incomplete backup.